IN VITRO ACTIVITY OF ANTISEPTICS USED ALONE OR IN SEQUENTIAL COMBINATION AGAINST METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS BIOFILMS ON TITANIUM

Introduction Prosthetic joint infections are predominantly associated with mature bacterial biofilms, particularly those formed by methicillin resistant Staphylococcus aureus (MRSA), which exhibit marked tolerance to antimicrobial treatments. Intraoperative antiseptic irrigation represents a potential adjuvant to surgical debridement to reduce bacterial burden and biofilm biomass. This study aimed to evaluate in vitro the activity of six antiseptics used alone or in sequential combination against MRSA biofilms formed on titanium surfaces. Materials and methods MRSA biofilms (ATCC 33951) were grown for 24 h on Ti6Al4V titanium coupons in TGN medium (TSB supplemented with 1% glucose and 2% NaCl). Coupons were exposed to six antiseptics (povidone iodine, hydrogen peroxide, chlorhexidine, taurolidine, polyhexanide, and an antibiofilm wound lavage solution*) at concentrations based on previously determined minimal biofilm eradication concentrations, for exposure times of 1, 3, 5, and 10 minutes. Sequential combination therapy consisted of the application of a first antiseptic, followed by two phosphate buffered saline rinses, and then exposure to a second antiseptic. Antiseptics selected for combination therapy were those showing the highest activity in monotherapy. Outcomes included colony forming unit (CFU) counts, biofilm biomass quantification, and fluorescence microscopy. Seven combinations involving hydrogen peroxide 1.5%, povidone iodine (1% and 0.35%), and an antibiofilm wound lavage solution* were tested. Results In monotherapy, povidone iodine at 2.5% and undiluted antibiofilm wound lavage solution* reduced bacterial load by 3–4 log 10 CFU per coupon from 3 and 5 minutes of exposure, respectively. Biofilm biomass was reduced by 50–80% after 1 minute of exposure to hydrogen peroxide 1.5%, undiluted taurolidine, and povidone iodine at 0.35% and 1%. All seven sequential combinations resulted in reductions greater than 3 log 10 CFU per coupon. Combinations initiating with the antibiofilm wound lavage solution* did not result in a significant reduction in biofilm biomass, whereas sequences starting with hydrogen peroxide or povidone iodine maintained a substantial antibiofilm effect. Conclusion Several antiseptics demonstrated rapid and significant antibiofilm activity against MRSA biofilms on titanium surfaces when used alone or in sequential combination, supporting their potential role in intraoperative irrigation during prosthetic joint infection management. *Bactisure